Expression of LHX3 and SOX2 during mouse inner ear development.

A cascade of transcription factors is believed to regulate the coordinate differentiation of primordial inner ear cells into the subtypes of hair cells and supporting cells. While candidate genes involved in this process have been identified, the temporal and spatial patterns of expression of many of these have not been carefully described during the extended period of inner ear development and functional maturation. We systematically examined the expression of two such transcription factors, LHX3 and SOX2, from the time of hair cell terminal mitoses into adulthood. We show that LHX3 is expressed specifically in auditory and vestibular hair cells soon after terminal mitoses and persists into the adult in vestibular hair cells. While SOX2 expression is widespread in the inner ear sensory epithelia prior to hair cell differentiation, it has a unique pattern of expression in the mature auditory and vestibular organs.